RPN Research has recently developed a new instrument called the Bioelectric Field Imager (BFI) that allows us to measure the surface potential of the skin without touching it. We have used the BFI to map the lateral electric field surrounding a skin wound in mice and propose here to determine its usefulness for the diagnosis of skin tumors. We have known for 160 years that human skin drives ionic current out of regions where the integrity of the epidermis has been breached (DuBois-Reymond, 1843). This current then passes between the stratum corneum and the epidermis, generating a lateral electric field surrounding the lesion. Regions of intact, healthy skin do not exhibit such lateral electric fields so the presence of such fields is a strong indicator of a wound or lesion. If lesions such as melanoma or basal cell carcinoma reduce the resistance across the epidermis, we would expect to detect lateral electric fields near these tumors. We have used a mouse model system in which we induce a melanoma to develop by injecting B16 murine melanoma cells beneath the skin. We present preliminary measurements of lateral electric fields associated with these melanomas. Fields of 600 mV/mm and greater are associated with these melanomas as early as 1 day after we inject the melanoma cells beneath the skin. Much more needs to be done to establish the reliability of this approach. We propose to conduct a histological study to correlate the measured electric field strength with melanoma size and will establish the reliability of this technique for the diagnosis of skin lesions. We will also conduct clinical investigations on humans to determine if the BFI can distinguish between benign and malignant skin lesions. If so, the BFI could improve human health by early detection of skin disease and may provide a routine diagnostic device that could reduce the number of biopsies necessary. There are very few medical devices to aid dermatologists and other physicians in the diagnosis of skin disease at the present time. They must rely on past experience and the results of biopsies performed on each patient (Farmer and Hood, 2000). The BFI can provide additional information about the suspected lesion that may prove very informative in making the diagnosis. The 3 most common forms of skin cancer, basal cell carcinoma, squamous cell carcinoma and malignant melanoma all cause disruptions in the epidermis and would be expected to generate local electric fields that could be detected by the BFI. [unreadable] [unreadable] [unreadable]